1. Field of the Disclosure
This invention relates generally to advances in medical systems and procedures for prolonging and improving human life. More particularly, this invention relates to a system and method for insertion of a cannula into the intervertebral disc and the insertion of a thermal probe into the disc material to heat the intervertebral disc thereby relieving and treating abnormalities or pain related to the disc.
2. Background of the Disclosure
The use of radiofrequency electrodes for ablation of tissue in the body or for the treatment of pain is known. In a typical situation, a radiofrequency probe or a resistive heating probe commonly constructed in an elongated, cylindrical configuration is inserted into the body to a target tissue which is to be treated or ablated. In the case of a radio frequency probe, there is typically an exposed conductive tip portion and an insulated portion of the probe. When connected to an external source of radiofrequency power, heating of tissue occurs at the exposed conductive portion of the probe, thereby therapeutic changes in the target tissue near the conductive tip are created by the elevation of temperature of the tissue near the tip. Thermal probes can also be made by resistive heating of a portion of the probe so as to heat surrounding tissue by thermal conduction. By reference, the products of Radionics, Inc., located in Burlington, Mass., include radiofrequency generators and electrode systems of varied configurations that are commercially available. A paper by Cosman, et al., entitled “Theoretical Aspects of Radiofrequency Lesions in the Dorsal Root Entry Zone,” Neurosurgery, December 1984, Vol. 15, No. 6, pp. 945–950, describes aspects of tissue heating using radiofrequency electrodes and probes.
The use of thermal therapy in and around the spinal column is known. Also, the insertion of cannula into the intervertebral discs is commonly done for injection of contrast mediums to implement X-ray discograms. This technique is used to detect or diagnose abnormalities or damage to the intervertebral disc. The use of heating of an intervertebral disc to relieve pain is described in the patent entitled “Method and Apparatus for Heating an Intervertebral Disc for Relief of Back Pain” by Menno E. Sluijter and Eric R. Cosman, U.S. Pat. No. 5,433,739, issued Jul. 18, 1995, and in the patent entitled “Thermal Denervation of an Intervertebral Disc for Relief of Back Pain” by Menno E. Sluijter and Eric R. Cosman, U.S. Pat. No. 5,571,147, issued Nov. 5, 1996. Both U.S. Pat. Nos. 5,433,739 and 5,571,147 are incorporated herein by reference. In these patents, electrodes are described for either radiofrequency or resistive thermal heating of all or a portion of the intervertebral disc. Straight, curved, and flexible-tipped electrodes are described for this purpose. The thermal treatment of an intervertebral disc for the relief of back pain is also described within the patents cited above.
The use of a resistively heated probe adapted to be inserted into the intervertebral disc is described in the product line of the company Oratec Interventions, Inc., located in Menlo Park, Calif. The Oratec instrumentation includes a flexible catheter which is introduced into the nucleus pulposus and manipulated about an inner wall of the annulus fibrosis. A functional element of the catheter treats the nucleus pulposus tissue.
It is desirable to treat the posterior or posterior/lateral portion of the intervertebral disc for the indication of mechanical degeneration of the disc and discogenic back pain. Pain can be derived from degeneration or compression of the intervertebral disc in its posterior or posterior/lateral portions. There is some innervation of the intervertebral disc near the surface of the disc and also within its outer portion known as the annulus fibrosus. Fissures or cracks within the disc caused by age, mechanical trauma, or disc degeneration are believed to be associated with painful symptoms.
Thus, a configuration of insertion cannula to approach and enter the intervertebral disc and a thermal probe to be built into or associated with said cannula to adequately reach the posterior/lateral and posterior portions of the intervertebral disc is desirable. For safety, it is desirable that the surgeon have quantitative information about the placement of the cannula and thermal probe as it is placed in the disc. Risk of the probe kinking within the disc or straying outside of the disc could result in damage to the probe or injury to the patient. A simple and robust cannula and probe system for direct and confirmable placement at the posterior and posterior/lateral portion of the disc is desirable.